Elastic spacer for bundles of conductors

ABSTRACT

Elastic spacer for bundled conductors in overhead electric lines, of the type comprising an elastically deformable structure anchored to the individual conductors of the bundle by means of connecting clamps, said elastic spacer also performing a function of damping the Aeolian vibrations. Said connecting clamps of the elastic spacer extend in the form of rigid projections, the free ends of which are mutually associated through at least one intermediate rigid body to which they are anchored by means of springing hinge elements, each constituted by at least one short length of straight wire rope fixed securely to the two rigid parts to be connected.

I United States Patent 1 1 3,582,983

[72} Inventor Rodolfo Claren FOREIGN PATENTS Milan, Italy 1,215,784 11 1959 France 174 45 1 PP NO. 1.724 839,215 5/1952 Germany..... 174 146 1 Flled Jan-$1970 971,663 9/1964 Great Britain. 174/146 [45] Patented June 1, 1971 363,692 9/1962 Switzerland l74/l46 [73] Ass1gnec A. Salvi & C. S.p.A.,

Milan, ma Primary Exammer-Laram1e E. Askin 32] priority Feb 22, 1969 Attorney-Benjamin J. Barish 1331 Italy [31] l32l7A/69 [54] ELASTIC SPACER FOR BUNDLES 0F CONDUCTORS 5 Claims, 5 Drawing Figs ABSTRACT: Elastic spacer for bundled conductors in overhead electric hues, of the type comprising an elastically U65. deformable tru ture an hored to the individual conductors of l74/146 the bundle by means of connecting clamps, said elastic spacer [51] Int. Cl [102g 7/12, also performing a f ti f damping the Aeolian i i 2 7/14 Said connecting clamps of the elastic spacer extend in the [50] Field of Search 174/42, I46 f f rigid projections, the f ends f which are mutually associated throu h at least one intermediate rigid body to [56] References cued which they are nchored by means of springing hinge ele- UNITED STATES PATENTS ments, each constituted by at least one short length of straight 3,443,0l9 5/1969 Walker et a1. 174/42 wire rope fixed securely to the two rigid parts to be connected.

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- snmaors By 9 M Attorney ELASTIC SPACER FOR BUNDLES OF CONDUCTORS BACKGROUND OF THE INVENTION 1. Field of the Invention The use of bundles of conductors for main current-carrying and interconnecting overhead electric lines gives rise to the need to dispose spacing elements at suitable intervals along the line between elementary conductors of the same bundle, in order to avoid these conductors becoming crossed or superposed in any way one on top of the other.

These troubles may occur both owing to relative movements of one conductor with respect to the other due to different elongation, action of the wind, detachment of collars of ice. snow or other external forces of a mechanical nature, and owing to the electrodynamic effect of mutual attraction due to the short circuit currents which may occur in the line.

Spacers intended to connect the elementary conductors of a same bundle must therefore satisfy two opposite requirements: on the one hand, they must be sufficiently flexible not to damage the conductors at the point of attachment of the spacer when the conductors themselves are subjected to oscillations; on the other hand, they must be sufficiently robust to be able to withstand without permanent deformation the compression stresses due to the above-mentioned electrodynamic effect.

A further important problem being met in the use of bun dled conductors, is that relating to the damping of Aeolian vibrations, namely those vibrations being induced in the single conductors by the action of the wind.

2. Description of the Prior Art Italian Utility Model No. 47812 describes a spacer formed by a flexible ring preferably constituted by a steel cable. This spacer, due to its characteristics of compromise between flexibility and rigidity, withstands well the stresses originating from oscillations of the conductors and also those originating from the above-mentioned electrodynamic effect occurring on short circuits of the line, but nevertheless limited to short circuits with relatively low line voltages.

Italian Pat. application No. 16740 A/68, dated May 2|, 1968, of the same applicants, proposes, on the other hand, a spacer structure which also takes account of high short circuit currents and behaves in a differentiated manner in keeping with the stress. This structure is substantially a structure having sufi'icient flexibility where the stresses are low and which, beyond a predetermined flexure value, is transformed intoa substantially rigid system.

The problem of damping Aeolian vibrations has been the subject of many studies which have resulted in the construction of various dampers with oscillating counterweights in more or less complex and more or less improved forms. These dampers, which have proved to have optimum efficiency in electric lines having a single conductor or a bundle of two horizontally disposed conductors, for each phase, do not generally enable the same results to be obtained in electric lines having bundles of two vertically disposed conductors or of more than two conductors disposed in any manner per phase. This difference of behavior of the same dampers is explained by the different dynamic behavior of the bundle of conductors when they are connected by spacers having different flexibility and damping characteristics.

SUMMARY OF THE INVENTION The object of the present invention is an improved spacer structure which, in addition to performing the function of keeping the conductors of the bundle separated and spaced from one another with a differentiated behavior, since it takes account both of low stresses, due to oscillations or vibrations of the conductors, and of the electrodynamic effect with high short circuit currents, is adapted to perform a function of damping the vibrations induced in the conductors by the action of the wind.

The present invention, therefore, proposes a spacer structure with special elastic characteristics which, as has been LII said, also performs a function of damping the Aeolian vibrations. Although the damping effect of a single spacer is not generally as high as in the case of the more improved types of dampers, nevertheless, bearing in mind that a certain number of these spacers, distributed uniformly, is employed over a span of electric line, the total damping effect is sufficient to protect the conductors from the stresses due to Aeolian vibrations, even without the use of dampers. The spacer according to the invention, which comprises, in a known manner, an elastically deformable structure anchored to the conductors of the bundle by means of connecting clamps, is characterized in that said connecting clamps extend in the form of rigid projections, the free ends of which are mutually associated through at least one intermediate rigid body to which they are anchored by means of springing hinge elements, each constituted simply by at least one short length of wire rope fixed securely at one end to said intermediate rigid body and at the other end to the free ends of one of said projections.

In one described embodiment particularly for a bundle of three conductors, the projection of one of the connecting clamps is extended in the form of a rigid crosspiece, to the ends of which are hinged two intermediate rigid bodies, the projections of the other two clamps being also hinged to said rigid bodies. In a second described embodiment, particularly for a bundle of four conductors, to the ends of the projections of each of the clamps are hinged four corresponding intermediate rigid bodies, the latter being hinged in turn to a common central rigid body.

Moreover, the intermediate rigid body and said projections are preferably formed in the area of mutual hinging with opposed portions which, by coming to bear one against the other, are apt to limit the angle of oscillation of said hinge element.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is anyhow made more clear with reference to a number of preferred embodiments being provided, however, merely by way of example and illustrated in the accompanying drawings, wherein:

FIG. 1 shows diagrammatically a spacer according to the invention fitted to a bundle of four conductors and seen along the axis of the bundle; t

FIG. 2 shows diagrammatically a spacer according to the invention fitted to a bundle of three conductors;

FIG. 3 shows similarly a spacer according to the invention fitted to a bundle of two conductors;

FIG. 4 shows on a larger scale the detail of a connecting clamp and of the respective hinge element;

FIG. 5 shows the detail of FIG. 4 as seen in the direction of the arrow F.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As can be seen in FIG. 1, the clamps 2 of the elastic spacer are anchored to the conductors l of a bundle consisting of four conductors. Each clamp is extended in the form of a projection 2', the free end of which is joined to an intermediate rigid body 3 by means of a first hinge element 4. The longitudinal axis of each intermediate body 3 is directed substantially perpendicular to the longitudinal axis of the projection 2'.

Each'of the four intermediate bodies 3 is anchored in turn to a further central rigid body 5 through second hinge elements 6.

In the embodiment of FIG. 2, the structure of the spacer is more simplified. In fact, the projection 2" of one of the clamps 2 is extended in the form of a rigid crosspiece which also performs the function of a central body; the intermediate bodies 3 are hinged to this central body by means of hinge elements 6, as in the case of FIG. I, the intermediate bodies 3 being associated in turn with corresponding projections 2' by means of hinges 4.

In FIG. 3, the structure is further simplified, inasmuch as the 'intennediate element 3 is common to the two clamps and also performs the function of a central body.

As shown better in FIG. 4, each of the hinges 4 or 6 is constituted by at least one length of wire rope of predetermined length, the ends of which are fast with the two parts being hinged.' In the case of the hinges 4, the length of wire rope is fixed at one end to'the end of the projection 2' and at the other to the intermediate body 3, while in the case of the hinges 6 the length of wire rope is fixed at one end to the body 3 and at the other end to the central body 5.

According to the invention, for each hinge 4 or 6 it is possible to employ a single length of rope or a plurality of parallel lengths disposed in a plane containing the axis of the hinge. By suitable choice of the number of these lengths or pieces and/or of the length L of each thereof and/or of the diameter and stranding of the rope itself, it is possible to adjust the flexibility characteristics of the hinge within the desired limits. it has been found in practice that, for present requirements, optimum results are obtained with hinges constituted by a single piece of rope (see FIG. 5) with a length L ranging between 20 and 50 mm. and a diameter of l to 15 mm.

The fixing of the lengths of rope to the hinging parts, thus connected, can be done in any known manner, for example by incorporating said lengths of rope during the actual casting of the parts to be hinged, or by welding, by pressing or the like.

According to a preferred embodiment of the present invention, the parts connected by the hinges 4 and 6 have in the hinging area a conformation comprising opposed protube rances 7 which, by coming to bear one against the other, are apt to limit the angle of maximum oscillation of the hinge unit. The result obtained with this arrangement is that, under the high electrodynamic stresses due to short circuits of the line, or under other stresses of a transistory nature and of high value, the structure of the spacer closes up as far as the limit allowed by the stops 7, and becomes practically rigid and apt to prevent an excessive approach of the individual conductors in the bundle.

The distance H between the stops 7, under rest conditions of the structures, is also determined in keeping with the other mechanical characteristics of the line and with the electric loads to be withstood thereby; in practice it has been found that H may assume a value ranging between and 10 mm., also in relation to the length L.

It is understood in any case that the invention is not limited to the illustrated embodiments, but that many other variants different therefrom may be produced, without departing thereby from the scope of the invention itself.

Iclaim:

1. Elastic spacer for a bundle of three conductors in overhead electric lines, of the type comprising an elastically deformable structure anchored to the individual conductors of the bundle by means of a connecting clamp for each conductor, characterized in that said connecting clamps extend in the form of rigid projections the free ends of which are mutually associated through at least one intermediate rigid body to which they are anchored by means of springing hinge elements, each constituted by at least one short length of straight wire rope fixed securely to the two connected rigid parts, and further in that the projection of one of the connecting clamps is extended in the form of a rigid crosspiece, to the ends of which are hinged two intermediate rigid bodies, the projections of the other two clamps being also hinged to said rigid bodies.

2. Elastic spacer for a bundle of four conductors in overhead electric lines, of the type comprising an elastically deformable structure anchored to the individual conductors of the bundle by means of a connecting clamp for each conductor, characterized in that said connecting clamps extend in the form of rigid projections the free ends of which are mutually associated through at least one intermediate rigid body to which they are anchored by means of springing hinge elements, each constituted by at least one short length of straight wire rope fixed securely to the two connected rigid parts, and further in that to the ends of the projections of each of the clamps are hinged four corresponding intermediate rigid bodies, the latter being hinged in turn to a common central rigid body.

3. Spacer for at least two conductors in overhead electric lines, comprising, at least two clamps one for each of said two conductors, each clamp carrying a rigid projection extending from one side thereof, a central rigid body, at least two intermediate rigid bodies one for each of said two clamps, a first hinge element for each clamp and constituted of at least one short length of straight wire rope fixed securely between the free end of the rigid projection of its respective clamp and one side of its respective intermediate rigid body, and a second hinge element for each clamp and constituted of at least one short length of straight wire rope fixed securely between the other side of its respective intermediate rigid body and said central rigid body, the wire rope of each said second hinge element extending in a perpendicular direction to that of said first hinge element of its respective clamp.

4. A spacer as defined in claim 3, further including a third clamp for a third conductor, said third clamp being fixed securely to said central rigid body.

5. A spacer as defined in claim 3, further including a third and a fourth clamp for a thirdand a fourth conductor, there being a said rigid projection, first hinge element, intermediate rigid body, and second hinge element for each of said third and fourth clamps and connecting same to said central rigid body as with respect to said two clamps. 

1. Elastic spacer for a bundle of three conductors in overhead electric lines, of the type comprising an elastically deformable structure anchored to the individual conductors of the bundle by means of a Connecting clamp for each conductor, characterized in that said connecting clamps extend in the form of rigid projections the free ends of which are mutually associated through at least one intermediate rigid body to which they are anchored by means of springing hinge elements, each constituted by at least one short length of straight wire rope fixed securely to the two connected rigid parts, and further in that the projection of one of the connecting clamps is extended in the form of a rigid crosspiece, to the ends of which are hinged two intermediate rigid bodies, the projections of the other two clamps being also hinged to said rigid bodies.
 2. Elastic spacer for a bundle of four conductors in overhead electric lines, of the type comprising an elastically deformable structure anchored to the individual conductors of the bundle by means of a connecting clamp for each conductor, characterized in that said connecting clamps extend in the form of rigid projections the free ends of which are mutually associated through at least one intermediate rigid body to which they are anchored by means of springing hinge elements, each constituted by at least one short length of straight wire rope fixed securely to the two connected rigid parts, and further in that to the ends of the projections of each of the clamps are hinged four corresponding intermediate rigid bodies, the latter being hinged in turn to a common central rigid body.
 3. Spacer for at least two conductors in overhead electric lines, comprising, at least two clamps one for each of said two conductors, each clamp carrying a rigid projection extending from one side thereof, a central rigid body, at least two intermediate rigid bodies one for each of said two clamps, a first hinge element for each clamp and constituted of at least one short length of straight wire rope fixed securely between the free end of the rigid projection of its respective clamp and one side of its respective intermediate rigid body, and a second hinge element for each clamp and constituted of at least one short length of straight wire rope fixed securely between the other side of its respective intermediate rigid body and said central rigid body, the wire rope of each said second hinge element extending in a perpendicular direction to that of said first hinge element of its respective clamp.
 4. A spacer as defined in claim 3, further including a third clamp for a third conductor, said third clamp being fixed securely to said central rigid body.
 5. A spacer as defined in claim 3, further including a third and a fourth clamp for a third and a fourth conductor, there being a said rigid projection, first hinge element, intermediate rigid body, and second hinge element for each of said third and fourth clamps and connecting same to said central rigid body as with respect to said two clamps. 